In researching the various existing instant messaging system, and discussing their alternative styles and broad types, we were able to produce a list of requirements which reflected a combination of our desired functionality, and functionality which is common among instant messaging systems. The MoSCoW technique allowed us to track our progress by measuring our coverage, in terms of what had been implemented, of the four requirement priorities. In addition, prioritising our requirements in this way allowed us to focus on increasingly less essential features, knowing that a solid foundation had been created by our must have features.